There have been reported many classical chemical investigations on colloidal clay materials in the volcanic ash soils in Japan. It has been proved that the main constituent of clay fraction was allophane. In the present study, the inorganic colloidal fractions (<2μ) were separated from soils, taken from each horizon of soil profile at Taisho in Tokachi. Chemical and physical studies were carried out on these samples.Generaly, Al_20_3 was proved to be much as one of the principal materials throughout all samples, so the Si0_2/Al_20_3 ratio by the total analysis was small (1.6〜4.0). Moreover, the Si0_2/Al_20_3 ratios by TAMM's Reagent was low (0.5〜0.7) in surface soil and high (1.9) in lower soils. Total Al_20_3 and also the Al_20_3 insoluble in TAMM's Reagent were much in lower soils. The latter was estimated as the combined Al_20_3. So the degree of the presence of free or soluble Al_20_3 was greater in upper soils and smaller in lower soils. From the Differential Thermal Analysis curves of soil colloids from lower parts of profile, the presence of gibbsite was observed. Electron microscopic photographs of surface samples showed many needle crystalls of hydrated halloysite. The lines of X-ray diagram showed the presence of hydrated halloysite, gibbsite, allophane, goethite and boehmite. It was conclude that the principal constituent colloidal materials of these volcanic ash soils were hydrated sesquioxide, 1 : 1 latice clay material and allophane.

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1) The isolated wheat roots were grown in the sterile nutrient solution. The sterilysing method of the seeds was fully investigated. As the sterilizer of the plant seeds, calcium hypochlorite solution was superior to the other disinfectants in securing the sterility and the activity of the germination of seeds. 2) In order to see the influences of inorganic ions on the growth of the root itself, the isolated wheat roots were cultured in media containing different concentration levels of the inorganic ions for ten days. The results may be summarized as follows. 3) Omission of N0_3-, P0_4- and Mg-ions respectively did not bring about any notable effects on the growth along the main-axies. The fact that omission of these inorganic ions resulted in no poorer growth, may be due to the supply of the nutrients originated from the mature tissue during the germination process. When either Ca or K-ion was omitted, the influence of its deficiency was clearly found in the growth. The same was true for N0_3,if the shorter root tips were inoculated into the culture solution. It seems possible, therefore, that mature tissues are essential for the activity of meristematic tissues. 4) In case of increasing Ca- or Mg-ion concentration by four times, the roots falied to grow, though without significant difference in the same concentration of N0_3-, P0_4- and K-ions respectively. 5) When Mg was added excessively, the tips of the roots appeared brown and the growth was retarded severely. The development of abnormal symptoms by the presence of excess supply of Mg was cured by adding the optimum level of Ca-ion. This effect of Ca-ion suggests to be antagonistic to Mg-ion.

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In the preliminary report of these studies, it was pointed out that the yield of grain is comparatively constant throughout Japan, while the yield of straw decreases from the south to the north, so the grain-straw ratio (grain weight/straw weight) increases from the south to the north. Recently the dying of lower leaves at late stage of growth has come into the problem in the warm area in connection with the nutritional shrinkage in fall. The object of the present study is to ascertain the connection of the grain-straw ratio with the degree of the dying of lower leaves. Rice plants were cultured in 1953 under quite the same conditions as described in the first report. Samples were taken at the flowering stage from the south to the north. Studies were made by using the leaves on their main stem, because the physiological characters of the corresponding leaves on many tillers can be represented by the leaves on main stem. The following results were obtained. 1) Diagram of the condition of leaves on main stem at the flowering stage is given in Table 1. Number of leaves on main stem decreases from the south to the north. Number of dead leaves at flowering stage on main stem also decreases from the south to the north. So, number of vital leaves is almost the same in both cases. 2) In the case of rice plant in the south, the dying of lower leaves is remarkable and the lack of nitrogen in soil at late stage of growth seems to be the cause of this dying of lower leaves. In the case of rice plant in the north, the dying of lower leaves is slight and the low availability of phosphorus in soil at early stage of growth seems to have some connection to this dying of lower leaves. 3) The physiological conditions of vital leaves at the flowering stage are almost constant without regard to localities and weight of vital leaves at flowering stage is also almost constant. In brief, vital leaves of rice plants in every locality have almost the same qality and quantity and the ability of assimilation of rice plant after the time of flowering stage is almost the same without regard to the locality of rice plant. As the yield of grain is chiefly related to assimilation product after flowering, the yield of grain in every locality will be almost constant.So, the grain-straw ratio becomes smaller in the south than in the north.

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The aspects of phosphate fixation in pure chemical solution was covered in the previous paper of this series. The present paper dealt with the interaction between H_3P0_4 and montmollironite clays at various pH values. the minerals studied were TUYAMA-, ARIMA (pink)-, and ARIMA (yellow)-bentonites. The methods used for studying phosphate fixation were similar as those reported in the preceding papers and briefly are as follows : Five grams of mineral was mixed with 90ml of N/120 H_3P0_4 and adequate NaOH or HCl to adjust pH values. The mixture was incubated at 30℃ for 5days with occational shaking. The pH value of the mixture was determined with glass electrode and then the mineral was centrifuged, and the fixed phosphate was obtained from the difference between the amount of added phosphorus and that left in solution. The phosphorus determination was carried out by the Sherman's sulfonic acid method. As preliminary treatments the sample minerals were a) ground to pass a 100mesh sieve by means of a porcelain mortar and pestle ("ground Natural-clay"), b) suspended to pass a 0.25 mm sieve without grinding ("unground Natural-clay"), c) leached with 0.2N HCl("unground Hydrogen clay"), and d) leached with 0.2N HCl after grinding ("ground Hydrogen-clay "). The results obtained were as follows : 1) The interaction between H_3P0_4 and bentonites took place rapidly and reached equilibrium within a few days. 2) The lower the amount of phosphorus added, the higher the phosphorus fixation ratio, whereas, the amount of fixation was lower. 3) The pH range where the peak had appeared tended to shift towards alkaline side with decreasing phosphate concentration. 4) The grinding of bentonite exerted no influence upon the type of phosphate fixation. 5) A comparison between the fixation curves of the natural bentonite and the 0.2N HCl leached bentonite showed the fact that in the natural bentonite only one peak occurred at pH3,while in the leached bentonite besides the high peak at pH 3,and there was another peak at pH 6. It was assumed from the present experiment in some detail that these two peaks appeared at pH values of 3 and 6 were probably due to iron and aluminium, respectively. 6) Moreover, the retention of phosphate increased again at pH above 9,when the natural bentonite was used. On the other hand, in the leached bentonite there was no increase above pH 9. This increase in the alkaline range was possibly regarded as due to the presence of calcium ion. 7) ARIMA (yellow)-bentonite in natural state had shown alreadly two peaks at pH 3 and 6,before the treatment by 0.2N HCl leaching, hence this mineral was much more rich in exchangeable aluminium ion than the other clay minerals employed.

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From the results of our experiments on the amounts of NH_4,leached out from the stagnated paddy soils in the pots with or without growing paddy plant, the following points are discussed. In the early stage of paddy growth, from 25 to 30 days after transplanting, the concentration of NH_4 in the percolating soil solution would be an important factor to govern whether the tillering would be delayed or promoted, and in the case of our experiments it can be said that the concentration of NH_4 should not be less than 10 ppm, at least, during three weeks after transplanting. D pending upon the degree of percolation in paddy field, the begining of irrigation and also the optimum period of transplanting must be determined in reference to keeping the concentration of NH_4 to a above extent. On the other hand, the root of rice plant can utilize NH_4 not only in surface soil but also in subsoil, when elongated. And, in the subsoil, a certain stimulating action of the root to anaerobic bacteria, causing the production of NH_4,is expected. Facility of the root to penetrate into the subsoil must not be neglected, when we reckon the factors for a good growth or a high yield of rice plant, besides the NH_4 concentration and others.

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The object of this study is to clarify the physiological relation between α-Naphthylamine and plant life. Author took up a rice plant for this purpose and treated it by water and soil culture. The experiment consisted of plots containing 200,100,50,30,10,5,3,and 1 ppm of α-Naphthylamine in each 1/20000 tan Wagner's pot and the control. In water culture no fertilizer was nsed, only naphthylamine is dissolved in distilled water, and in soil cultre, plants were grown in quartz sand and sandy loam, with fertilizer. The object of the former is to make out the influence upon a young stage of plants, and that of the latter is to observe the inflnence throughout the whole stages of life. The results obtained are summerized as follows. (1) In the younger stage of growth, the accordance with strength of solution increased both the length and weight of roots (viz 8〜20% of length, 6〜11% of weight) as compared with the control. α-Naphthylamine were sedimented as reddishviolet precipitation of oxy-Naphthylamine on the roots by oxidobelity of roots which did not cause any physiological hindrance. (2) On the plots between 30〜200ppm increase of 8〜23% in tillers and 4〜7% in number of ears was observed moreover, both of these were distinctly increased in accordance with the thickness. (3) Concerning the influence on the hulled grains, application of α-naphthylamine was nearly correlated to the effective stems ratio and gave little increase in yield of grains. As for a total yield, plots between 30〜50 ppm were better.

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